The lateral masses are ovoid masses whose long axes converge anteriorly.  Each has superior and inferior surfaces that bear superior and inferior articular facets, respectively.  On the medial surface of each lateral mass is a roughened area with vascular foramina and a tubercle to which the transverse band of the cruciform ligament (transverse ligament of atlas) attaches.  Rectus capitis anterior attaches to the anterior surface of the lateral mass.